Fig. 8. Surgical removal of extensive perineal melanoma lesions can be a satisfying and logical approach and serves to prolong the life of the horse and improve its welfare. This procedure can be carried out in stages or using different treatment methods. Conventional sharp surgical excision is usually safe and practical but laser and cryosurgery can be used also to good effect. A, This 12-year-old Welsh cross mare developed multiple melanoma lesions over a period of 8–9 years. The horse was having defecation problems and the owner also noticed that the tumors had “turned white/blue”. B, Sharp surgery was used to remove the bulk of the melanoma masses dorsal to the anus. The wounds were left open as far as possible. C, Two months later the horse was reassessed and the surgical wound was healing well. A further laser surgery was then carried out to remove the rest of the lesions. Assessment at 12 months showed no recurrence and no new lesions. D, Following the healing of the first surgical site, the remaining melanoma lesions were removed by laser surgery. These sites healed slowly but the outcome was very satisfying. Some 4 years later, a few more very small lesions were removed by laser again.
Cryosurgery
Cryonecrosis of melanoma lesions is a fast but rarely effective method of treatment. Lesions that are ulcerated and that bleed significantly can be managed by careful and repeated cryo- surgery. On the eyelids, however, this is proba- bly not advisable because of the consequent scarring.
Cimetidine
Oral cimetidine therapy has been reported to be successful in some cases of melanoma.8 Cimeti-
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dine reportedly acts through its effects on T-Killer cells and was administered by mouth at 3.5 mg/kg (q12h) or 7.5 mg/kg (q24h). However, its value in specific types of melanoma such as palpebral and ocular melanoma is not reported independently. The reported efficacy from one paper has not been replicated by other subsequent studies and the gen- eral consensus now is that it is not an effective treatment and cannot be justified on current evi- dence.9 Treatment can possibly be justified for up to 6 weeks; if no change is detected by 3 weeks, there
